Reaction-diffusion · deepseek-v4.1-flash

Let me build this. I'll create a single index.html with a Gray-Scott simulation. Then run it in browser and verify.

Let me write the file.

Now let's run it in the browser.

The simulation is evolving. At t=48 one blob, at t=176 it split into 4 spots — classic Gray-Scott mitosis. Good.

Now I need to verify interaction: seed separate region with pointer, check added region affects following frames. Also pause/resume, reset.

Let me test with debug hooks. But I can't run JS directly via browser tool except through clicks. Let me use click and inspect. Actually I can use the browser click. But to sample fields, I need to execute JS. There's no eval action. Let me check whether inspect returns console. I can add console logging.

Actually I can use the pointer click via browser click action. Let me click at a location and observe screenshot. Let me also test pause/resume.

Let me first click at off-center location and take screenshot quickly. The timing: steps at 8/frame, ~60fps = 480 steps/sec. By the time I screenshot it may have evolved a lot. That's fine.

Let me click at around (350,300) canvas coordinates. Canvas displayed roughly x 288-912, y 64-688. So a click at (400,300) maps to grid ~ (0.18*192, 0.38*192) ≈ (35,73). Good.

Let me click and screenshot. Also test pause.

Let me do click then screenshot.

The click seeded a new region at upper-left, and it grew. The central pattern evolved into an organic coral/branching shape. 

Now test pause and reset. Pause, capture t, wait, capture t again in screenshot to confirm no change. Let me click Pause button at roughly (532, 720). Then screenshot, then wait and screenshot again. The browser screenshot itself takes time. Let me pause and check stat text.

Paused, button now says "Resume", t frozen at 4528. The injected region evolved into its own shape.

Now test resume increases t. Click Resume. Then reset.

Resumed, t increased to 4536, button back to Pause. Now reset.

Reset restored the initial central seed (t=8 at screenshot, reset set t=0 then a few frames). The central seed is exactly the same square as the initial scene. 

Everything works. Now let me verify the "sample early field evolution" and "seed a separate region affects following frames" numerically. I did visually. But let me confirm the initial seed is identical to the initial scene. The requirement: "compare the restored central seed with the initial scene." I saw initial scene's central blob at early time (first inspect screenshot showed 4 spots at t=200... hmm, the very first inspect was at t=200 so I didn't see the initial square). But the reset seed is clearly the central square at t=8, which is the defined initial seed. Good enough.

One thing to verify: the initial scene. Let me reload to see initial seed at frame 1. Actually reload gives t=some small. Let me reload and screenshot.

Also, I want to check performance: 192x192 x 8 steps per frame at 60fps = ~1.77M cell-updates per frame. That's fine in JS.

Let me reload and take a quick screenshot to confirm initial state.

Initial scene after reload at t=40: central seed with a subtle halo starting to form. Matches the reset scene's restored central seed (also central square + halo at t=8). Good.

Everything verified. No console errors throughout. The implementation is complete.

Let me quickly note unverified behaviors: wrapping at boundaries (not visually tested), fast drag interpolation, long-term stability/performance. I'll report.

Actually, let me double check one potential concern: `pointerleave` sets pointerDown=false, which with pointer capture could be an issue but fine.

Done. Report.